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That is an unused engine speed sensor mounting pad. ...
The "gears" you see/feel inside the hole, is the flywheel ring gear for the starter motor. The teeth on the ring gear, pass close to a magnet with a coil of magnet wire formed around the pole/core.(IE, the sensor if present,) When the engine is running, the gear teeth moving toward then away from the magnetic pole, generates an AC sine wave voltage in the coil winding and connected load circuit, where the frequency of the AC voltage varies with engine speed. That function is provided be the G28, using a different "reluctor wheel", for the AMB, it's inside the crankcase.
The hole is a peep hole to find the TDC mark on the flywheel when doing a TB job or something else that requires one to find TDC. There are 3 marks to line up when opening the motor. The TDC mark on the cam pulley, crank pulley, and the flywheel. Thats where you look to find the flywheel mark.
The timing check view hole you refer to, is not a milled flat pad, like the picture shows, in addition, the threaded bolt hole is used to clamp the sensor in the hole, also notice the stepped shoulder machined into the casing, that accommodates the sensor O ring seal.
The view port for aligning timing marks, is not a precision machined feature in the case casting, it's just an "as cast" hole, fitted with a rubber plug at the factory.
The timing check view hole you refer to, is not a milled flat pad, like the picture shows, in addition, the threaded bolt hole is used to clamp the sensor in the hole, also notice the stepped shoulder machined into the casing, that accommodates the sensor O ring seal.
The view port for aligning timing marks, is not a precision machined feature in the case casting, it's just an "as cast" hole, fitted with a rubber plug at the factory.
Bummer I've been trying to mount the new sensor in that hole... Couldn't figure out why the bolt and sensor wouldn't got back in flush and the sensor was touching the flywheel. Thankyou!! I thought I'd lost a spacer :-S was about to try and buy one. I thought something must of happened with the bolt or the hole because it wouldn't screw in so I got the bolt tapped to fit the other sensor hole. What a learning experience. Now I need a new bolt and another sensor cause we damamged the mount bracket. It looks like the right hole!! Funny I couldn't figure out why the bolt fit in another hole near that one... It was probably the right one.
Great post guys, wish I read it last night!
Hey guys my spedo stop working recently and I got the new speed sensor for the tranny and I found that same whole u are talking about, but mine has a cap just like the top of the tss. I got confused becaus to my understanding that's the spot where the sensor would be but it had no connector just a plan plasting cap with the same locking mechanism as the sensor , the long arm with a head at the end that inserts in to a small cap after turning the sensor counter clock wise.
That's where that cap is in my car and where according to this picture the sensor should go. ???
09-16-2008, 05:02 AM
Audi probably had a sensor(different speed sensor) at some point
